1. Field of the Invention
The present invention relates to an endoscope in which a distal end cover, which is integrally molded from a plurality of kinds of resin, is bonded and fixed to a distal end rigid portion configuring a distal end portion of an endoscope insertion portion.
2. Description of the Related Art
An endoscope is widely used in a medical field and an industrial field. In the endoscope, a target of a diagnosis or an observation is inside a living organism, plant facilities, or the like. Therefore, when an endoscopic observation is performed, a light source for illuminating an observation target is necessary.
A general endoscope device includes an endoscope and a light source device, which is an external device of the endoscope. Illumination light emitted by the light source device is supplied to a light guide provided in the endoscope. The supplied illumination light is transmitted by the light guide. The transmitted illumination light is emitted from an illumination window provided on a distal end side of an insertion portion of the endoscope and illuminates the observation target.
In general, the illumination window is water-tightly fixed to a through-hole formed in a distal end cover having insulating properties. The distal end cover, to which the illumination window is fixed, is integrally fixed to a distal end rigid portion made of metal such as stainless steel. The distal end rigid portion configures a distal end portion of the insertion portion.
In recent years, an endoscope 5 is proposed in which a distal end cover 3 is bonded and fixed, with an adhesive 4, to a distal end rigid portion 2 made of metal configuring a distal end portion 1 as shown in FIGS. 1 and 2. The distal end cover 3 is configured by, for example, integrally molding a plurality of kinds of resin using two color molding. More specifically, the distal end cover 3 is configured by integrating a first molded portion 6 and a second molded portion 7. The first molded portion 6 is formed of a transparent first resin member including an illumination window portion 6w. The second molded portion 7 is formed of a colored second resin member configuring a light blocking portion.
In the endoscope 5, illumination light transmitted by a light guide 10 is transmitted through a lens for illumination 11 and the illumination window portion 6w of the first molded portion 6 and emitted toward an observation target. Reference numeral 12 denotes an observation optical portion, reference numeral 13 denotes a lens barrel, reference numeral 14 denotes an optical member for observation, reference numeral 15 denotes a hole for treatment instrument channel, reference numeral 16 denotes a nozzle, and reference numeral 17 denotes a hole for air/water feeding. As shown in FIG. 3, cracks 9a and 9b are likely to occur on boundary surfaces 8a and 8b between the first molded portion 6 and the second molded portion 7 in a vicinity of the adhesive 4 of the distal end cover 3.